linux-kernel - [tip:sched/core] sched/cpufreq: Annotate cpufreq_update_util_data pointer with _

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Message-ID: <tip-b10abd0a8859493a93c6b8020f2be2587557749d@git.kernel.org>
Date:   Wed, 3 Apr 2019 03:46:13 -0700
From:   "tip-bot for Joel Fernandes (Google)" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, tglx@...utronix.de, rostedt@...dmis.org,
        josh@...htriplett.org, luc.vanoostenryck@...il.com, efault@....de,
        joel@...lfernandes.org, torvalds@...ux-foundation.org,
        hpa@...or.com, jiangshanlai@...il.com, morten.rasmussen@....com,
        linux-kernel@...r.kernel.org, paulmck@...ux.ibm.com,
        mathieu.desnoyers@...icios.com, peterz@...radead.org
Subject: [tip:sched/core] sched/cpufreq: Annotate cpufreq_update_util_data
 pointer with __rcu

Commit-ID:  b10abd0a8859493a93c6b8020f2be2587557749d
Gitweb:     https://git.kernel.org/tip/b10abd0a8859493a93c6b8020f2be2587557749d
Author:     Joel Fernandes (Google) <joel@...lfernandes.org>
AuthorDate: Wed, 20 Mar 2019 20:34:23 -0400
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 3 Apr 2019 12:34:31 +0200

sched/cpufreq: Annotate cpufreq_update_util_data pointer with __rcu

Recently I added an RCU annotation check to rcu_assign_pointer(). All
pointers assigned to RCU protected data are to be annotated with __rcu
inorder to be able to use rcu_assign_pointer() similar to checks in
other RCU APIs.

This resulted in a sparse error:

  kernel//sched/cpufreq.c:41:9: sparse: error: incompatible types in comparison expression (different address spaces)

Fix this by annotating cpufreq_update_util_data pointer with __rcu. This
will also help sparse catch any future RCU misuage bugs.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
[ From an RCU perspective. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Paul E. McKenney <paulmck@...ux.ibm.com>
Cc: Josh Triplett <josh@...htriplett.org>
Cc: Lai Jiangshan <jiangshanlai@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@...il.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Mike Galbraith <efault@....de>
Cc: Morten Rasmussen <morten.rasmussen@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: keescook@...omium.org
Cc: kernel-hardening@...ts.openwall.com
Cc: kernel-team@...roid.com
Link: https://lkml.kernel.org/r/20190321003426.160260-2-joel@joelfernandes.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/cpufreq.c | 2 +-
 kernel/sched/sched.h   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/cpufreq.c b/kernel/sched/cpufreq.c
index 835671f0f917..b5dcd1d83c7f 100644
--- a/kernel/sched/cpufreq.c
+++ b/kernel/sched/cpufreq.c
@@ -7,7 +7,7 @@
  */
 #include "sched.h"
 
-DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
+DEFINE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data);
 
 /**
  * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index efa686eeff26..713715dd00cf 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2185,7 +2185,7 @@ static inline u64 irq_time_read(int cpu)
 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 
 #ifdef CONFIG_CPU_FREQ
-DECLARE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
+DECLARE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data);
 
 /**
  * cpufreq_update_util - Take a note about CPU utilization changes.